RL78/G1H CHAPTER 13 A/D CONVERTER
R01UH0575EJ0120 Rev. 1.20 Page 316 of 920
Dec 22, 2016
13.8 SNOOZE Mode Function
In the SNOOZE mode, A/D conversion is triggered by inputting a hardware trigger in the STOP mode. Normally, A/D
conversion is stopped while in the STOP mode, but, by using the SNOOZE mode, A/D conversion can be performed
without operating the CPU by inputting a hardware trigger. This is effective for reducing the operation current.
If the A/D conversion result range is specified using the ADUL and ADLL registers, A/D conversion results can be
judged at a certain interval of time in SNOOZE mode. Using this function enables power supply voltage monitoring
and input key judgment based on A/D inputs.
In the SNOOZE mode, only the following conversion mode can be used:
• Hardware trigger wait mode (select mode, one-shot conversion mode)
Caution That the SNOOZE mode can only be specified when the high-speed on-chip oscillator clock is
selected for f
CLK.
Figure 13 - 28 Block Diagram When Using SNOOZE Mode Function
When using the SNOOZE mode function, the initial setting of each register is specified before switching to the STOP
mode. (For details about these settings, see 13.7.3 Setting up hardware trigger wait mode
Note 2
.) At this time, bit
2 (AWC) of A/D converter mode register 2 (ADM2) is set to 1. After the initial settings are specified, bit 0 (ADCE) of
A/D converter mode register 0 (ADM0) is set to 1.
If a hardware trigger is input after switching to the STOP mode, the high-speed on-chip oscillator clock is supplied to
the A/D converter. After supplying this clock, the system automatically counts up to the A/D power supply
stabilization wait time, and then A/D conversion starts.
The SNOOZE mode operation after A/D conversion ends differs depending on whether an interrupt signal is
generated
Note 1
.
Note 1. Depending on the setting of the A/D conversion result comparison function (ADRCK bit, ADUL/ADLL
register), there is a possibility of no interrupt signal being generated.
Note 2. Be sure to set the ADM1 register to E1H, E2H or E3H.
Remark The hardware trigger is event selected by ELC, INTRTC or INTIT.
Specify the hardware trigger by using the A/D Converter Mode Register 1 (ADM1).
A/D converter
Real-time clock (RTC),
12-bit interval timer
Hardware trigger
input
High-speed on-chip
oscillator clock
Clock generator
A/D conversion end
interrupt request
signal
Note 1
(INTAD)
Clock request signal
(internal signal)
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